can transcribe in the ui

lib/elixir_ai/audio/audio_processing.ex

@@ -0,0 +1,47 @@
+defmodule ElixirAi.AudioProcessing do
+  @moduledoc """
+  Public API for the demand-driven audio transcription pool.
+
+  Dispatch strategy:
+    1. Pick a random idle worker from the :available pg group.
+    2. If none are idle and the pool is below @max_workers, spawn a fresh worker
+       under AudioWorkerSupervisor and route the job directly to it.
+    3. If already at @max_workers, queue the job to a random existing worker via
+       its Erlang mailbox — it will process it when its current job finishes.
+
+  Scale-up is fully automatic (on demand). Scale-down is handled by each worker's
+  idle-timeout logic; workers exit after idling and the pool can reach 0.
+  """
+
+  @max_workers 10
+  @all_group :all
+  @available_group :available
+
+  @doc """
+  Submit audio for transcription. The result is delivered asynchronously to
+  `caller_pid` as:
+
+      {:transcription_result, {:ok, text} | {:error, reason}}
+  """
+  def submit(audio_binary, mime_type, caller_pid) do
+    case :pg.get_members(ElixirAi.AudioProcessingPG, @available_group) do
+      [] ->
+        all = :pg.get_members(ElixirAi.AudioProcessingPG, @all_group)
+
+        if length(all) < @max_workers do
+          {:ok, pid} =
+            DynamicSupervisor.start_child(ElixirAi.AudioWorkerSupervisor, ElixirAi.AudioWorker)
+
+          GenServer.cast(pid, {:transcribe, caller_pid, audio_binary, mime_type})
+        else
+          # At max capacity — overflow to a random worker's mailbox
+          GenServer.cast(Enum.random(all), {:transcribe, caller_pid, audio_binary, mime_type})
+        end
+
+      available ->
+        GenServer.cast(Enum.random(available), {:transcribe, caller_pid, audio_binary, mime_type})
+    end
+
+    :ok
+  end
+end